/*
 * Copyright 2007 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.collectplus.express.tools.barcode;

/**
 * <p>
 * Represents a 2D matrix of bits. In function arguments below, and throughout the common module, x is the column position, and y is the row position. The ordering is always x, y. The origin is at the
 * top-left.
 * </p>
 * 
 * <p>
 * Internally the bits are represented in a 1-D array of 32-bit ints. However, each row begins with a new int. This is done intentionally so that we can copy out a row into a BitArray very
 * efficiently.
 * </p>
 * 
 * <p>
 * The ordering of bits is row-major. Within each int, the least significant bits are used first, meaning they represent lower x values. This is compatible with BitArray's implementation.
 * </p>
 * 
 * @author Sean Owen
 * @author dswitkin@google.com (Daniel Switkin)
 */
public final class BitMatrix {

	// TODO: Just like BitArray, these need to be public so ProGuard can inline them.
	public final int width;
	public final int height;
	public final int rowSize;
	public final int[] bits;

	// A helper to construct a square matrix.
	public BitMatrix(int dimension) {
		this(dimension, dimension);
	}

	public BitMatrix(int width, int height) {
		if (width < 1 || height < 1) {
			throw new IllegalArgumentException("Both dimensions must be greater than 0");
		}
		this.width = width;
		this.height = height;
		this.rowSize = (width + 31) >> 5;
		bits = new int[rowSize * height];
	}

	/**
	 * <p>
	 * Gets the requested bit, where true means black.
	 * </p>
	 * 
	 * @param x
	 *            The horizontal component (i.e. which column)
	 * @param y
	 *            The vertical component (i.e. which row)
	 * @return value of given bit in matrix
	 */
	public boolean get(int x, int y) {
		int offset = y * rowSize + (x >> 5);
		return ((bits[offset] >>> (x & 0x1f)) & 1) != 0;
	}

	/**
	 * <p>
	 * Sets the given bit to true.
	 * </p>
	 * 
	 * @param x
	 *            The horizontal component (i.e. which column)
	 * @param y
	 *            The vertical component (i.e. which row)
	 */
	public void set(int x, int y) {
		int offset = y * rowSize + (x >> 5);
		bits[offset] |= 1 << (x & 0x1f);
	}

	/**
	 * <p>
	 * Flips the given bit.
	 * </p>
	 * 
	 * @param x
	 *            The horizontal component (i.e. which column)
	 * @param y
	 *            The vertical component (i.e. which row)
	 */
	public void flip(int x, int y) {
		int offset = y * rowSize + (x >> 5);
		bits[offset] ^= 1 << (x & 0x1f);
	}

	/**
	 * Clears all bits (sets to false).
	 */
	public void clear() {
		int max = bits.length;
		for (int i = 0; i < max; i++) {
			bits[i] = 0;
		}
	}

	/**
	 * <p>
	 * Sets a square region of the bit matrix to true.
	 * </p>
	 * 
	 * @param left
	 *            The horizontal position to begin at (inclusive)
	 * @param top
	 *            The vertical position to begin at (inclusive)
	 * @param width
	 *            The width of the region
	 * @param height
	 *            The height of the region
	 */
	public void setRegion(int left, int top, int width, int height) {
		if (top < 0 || left < 0) {
			throw new IllegalArgumentException("Left and top must be nonnegative");
		}
		if (height < 1 || width < 1) {
			throw new IllegalArgumentException("Height and width must be at least 1");
		}
		int right = left + width;
		int bottom = top + height;
		if (bottom > this.height || right > this.width) {
			throw new IllegalArgumentException("The region must fit inside the matrix");
		}
		for (int y = top; y < bottom; y++) {
			int offset = y * rowSize;
			for (int x = left; x < right; x++) {
				bits[offset + (x >> 5)] |= 1 << (x & 0x1f);
			}
		}
	}

	/**
	 * A fast method to retrieve one row of data from the matrix as a BitArray.
	 * 
	 * @param y
	 *            The row to retrieve
	 * @param row
	 *            An optional caller-allocated BitArray, will be allocated if null or too small
	 * @return The resulting BitArray - this reference should always be used even when passing your own row
	 */
	public BitArray getRow(int y, BitArray row) {
		if (row == null || row.getSize() < width) {
			row = new BitArray(width);
		}
		int offset = y * rowSize;
		for (int x = 0; x < rowSize; x++) {
			row.setBulk(x << 5, bits[offset + x]);
		}
		return row;
	}

	/**
	 * This is useful in detecting a corner of a 'pure' barcode.
	 * 
	 * @return {x,y} coordinate of top-left-most 1 bit, or null if it is all white
	 */
	public int[] getTopLeftOnBit() {
		int bitsOffset = 0;
		while (bitsOffset < bits.length && bits[bitsOffset] == 0) {
			bitsOffset++;
		}
		if (bitsOffset == bits.length) {
			return null;
		}
		int y = bitsOffset / rowSize;
		int x = (bitsOffset % rowSize) << 5;

		int theBits = bits[bitsOffset];
		int bit = 0;
		while ((theBits << (31 - bit)) == 0) {
			bit++;
		}
		x += bit;
		return new int[] { x, y };
	}

	/**
	 * @return The width of the matrix
	 */
	public int getWidth() {
		return width;
	}

	/**
	 * @return The height of the matrix
	 */
	public int getHeight() {
		return height;
	}

	public boolean equals(Object o) {
		if (!(o instanceof BitMatrix)) {
			return false;
		}
		BitMatrix other = (BitMatrix) o;
		if (width != other.width || height != other.height || rowSize != other.rowSize || bits.length != other.bits.length) {
			return false;
		}
		for (int i = 0; i < bits.length; i++) {
			if (bits[i] != other.bits[i]) {
				return false;
			}
		}
		return true;
	}

	public int hashCode() {
		int hash = width;
		hash = 31 * hash + width;
		hash = 31 * hash + height;
		hash = 31 * hash + rowSize;
		for (int i = 0; i < bits.length; i++) {
			hash = 31 * hash + bits[i];
		}
		return hash;
	}

	public String toString() {
		StringBuffer result = new StringBuffer(height * (width + 1));
		for (int y = 0; y < height; y++) {
			for (int x = 0; x < width; x++) {
				result.append(get(x, y) ? "X " : "  ");
			}
			result.append('\n');
		}
		return result.toString();
	}

}
